WordPress Plugin vs Functions.php file (Which is better?)

We are often asked by users whether they should install a WordPress plugin or add code to their theme’s functions.php file? Some users believe that adding code is always the better method for performance, but that’s actually not true. In this article, we will explain the pros and cons of WordPress plugin vs functions.php file and which method is better.

Some users feel concerned about installing too many plugins, and how it may affect their website speed and WordPress security. Others worry that adding custom code can break their website, and they may not be able to easily fix it.

Let’s compare both solutions to figure out which one is better for WordPress performance.

Pros and Cons of functions.php File

Functions file in WordPress allows theme developers to define custom functionality for their theme. This file acts like a giant WordPress plugin and can be used to add any other custom code snippets you may want to add to your website.

Here are the advantages of adding custom code to your theme’s functions.php file.

Pros

You can easily use built-in theme editor in admin area to edit functions.php file

You can copy and paste all code snippets in one file

You get a chance to study the code and learn how it works

However, there are also some disadvantages of using functions.php file to save all your custom functionality.

Cons

Your custom code will not work if you switch themes

Unless you are using a child theme, updating your theme will overwrite functions.php file

It becomes harder to understand where theme code ends and where your custom code begins

Some code snippets can be too large and need additional scripts and styles

Here are some advantages of using a WordPress plugin instead of adding code to your functions file.

Pros

A WordPress plugin doesn’t depend on your theme

If it is the same code, then it would have the same performance impact as functions file

It is easier to disable, update, or reinstall as needed

Easier to manage as you know what each plugin does from its description

Now, we are not saying that installing all WordPress plugins is good. There are some disadvantages as well.

Cons

You will have to install updates for another plugin

Plugin author could abandon the plugin in the future specially if it’s free

You wouldn’t get to practice with the code

WordPress Plugin vs Functions File – Which One is Better?

If there is a WordPress plugin with the same code, then we believe that using a plugin is a better choice.

In terms of performance, it does not matter where the code runs. Whether it loads from functions.php file or as a separate plugin, if it is the same code, then it will have the same performance impact.

Managing separate plugins is much easier than editing a single large functions file. Adding random code snippets in the same file even when they are not related or dependant on each other makes things complicated.

If you choose a plugin, then you can benefit from future updates which may improve performance, fix bug, or patch security vulnerability.

When Should I Add Code to Functions.php File?

If the functionality you are trying to add is not available as a plugin and the code snippet is really simple, then you can add it to your theme’s functions file.

Another possible scenario is when you are adding functionality that is related to your WordPress theme or child theme. For example, creating new image sizes, showing dates, adding custom code before or after content, and more.

We hope this article helped you understand WordPress plugin vs functions.php file and which one is better. You may also want to see our beginner’s guide on how to choose the best WordPress plugins for your website.

Most of the articles I’ve read have been about whether to put your own code (or the code you’re copying from a tutorial) into functions.php or a plugin. This one seems to focus more on the question of whether to find an existing plugin or add code to functions.php. The point is well made (and I’ve made it myself) that if your code and a plugin author’s code are essentially the same, they will put exactly the same load on your site. But whether you write the code or copy the code from elsewhere, if you want it to be available to other themes, it should go into a plugin.

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